I found a post when googling which kind of talks about the situation.
Basically from what i have read here and there that although C of E Vicars could marry any couple in theory the powers that be want to change the law so loopholes are removed.
It seems best to get in contact with the offices mentioned.
First of all the marriage has to be with a licence and this may have to be granted by diocesan Bishop through the office of the Diocesan Registrar or a speical licence at the discretion of the Archbishop of canterbury (only in exceptional circumstances) or a superintendents registrar certifiacte (which will need to be refered for a COA to be granted as this is the same in effect as cival marriage process except you marry in church). All of this is also currently under review by the general synod who are considering changes to be made the marriage law.
I think the COA was more for those brits who wished to marry a person here on a non fiancee or spouse visa ie work, tourist or student visa.
Hope this helps although brought up a C of E im a bit out of touch with how the church works.
